For example, an intake manifold which is a member in an intake system in an engine is mounted to a sidewall of a cylinder head into which an intake port opens, as described in Japanese Patent Application Laid-open No.6-129316. The high-pressure fuel supply means for supplying fuel of a high pressure to the fuel injection valve provided in the intake manifold is mounted to an engine body such as a cylinder block, and the fuel injection valve provided in the intake manifold and the high-pressure fuel supply means are connected to each other by a fuel piping.
The above known engine suffers from the following problems. It is necessary to separately carry out the assembling of the intake manifold in the engine and the assembling of the high-pressure fuel supply means at the time of performing assembling or maintenance of the engine. Moreover, after completion of such assembling, it is necessary to carry out a piping operation for connecting the fuel injection valve provided in the intake manifold and the high-pressure fuel supply means to each other, and hence, a lot of time is required for such operation.